Project Summary/Abstract Diabetes is a leading cause of kidney failure, heart disease, stroke, visual impairment, and non-traumatic lower limb amputations. Diabetes self-care and preventative health services can prevent or delay many diabetes-related complications, yet few patients consistently receive all recommended services or engage in recommended self-care behaviors that are challenging to implement and sustain. Data increasingly support the role of patient-facing mobile health apps to modify health behavior, enhance self-care, and facilitate access to healthcare services for patients with diabetes. However, differences in the design and usability of diabetes mobile health apps have led to varying levels of patient engagement and inconsistent effects on glycemic control. Many diabetes mobile health apps lack efficacy due to one or more of the following: (a) absence of user-centered design, (b) lack of integration with the healthcare delivery system, (c) absence of key features to maximize patient engagement including patient-centered motivational strategies, and/or (d) failure to account for the unique needs of older patients and those with limited health literacy. Research supports user-centered design methods, usability testing, and synchronization with personal health records and patient web portals to maximize the effectiveness of mobile health apps and overcome existing challenges. In addition, a recently published framework identifies key strategies to promote patient engagement with mobile health apps that range from providing educational information to supporting behavior change with rewards using elements of game design and competition. By applying user-centered design methodology, key strategies for patient engagement, and usability assessments, we aim to: (1) design a patient-facing diabetes dashboard embedded within an existing patient web portal mobile app that is satisfying for a diverse group of patients (including older adults and those with limited health literacy) with type 2 diabetes to use, and (2) assess the usability over time of the patient-facing diabetes mobile dashboard developed in Aim 1. These objectives are in concert with the parent K23 application's goal of designing and testing a related diabetes dashboard embedded in a complimentary patient web portal desktop application. Since the start of the parent K23 award, a patient web portal mobile app was developed and is now available on iOS and Android mobile operating systems, providing an opportunity to translate the desktop application to the mobile platform. Mobile platforms offer an important compliment to desktop applications by increasing portability, convenience, and functionality, and bring with it new design opportunities related to screen size, hand gestures (e.g., swiping), notifications, and navigation. Finally, in accordance with the goals of the R03 award, the proposed research will further extend the design and usability assessment experience of the PI and produce data essential to the planning of a randomized controlled trial to be proposed in subsequent R01 application.